Dry-offset-printing process



VALENTIN D IErz. or

Patented Dec. 31, 1929 PATENT OFFICE OHIO No Drawing. Application filed. June 18, 1928, Serial No. 293,779,

My invention relates to an improved dryoffset printing process. It has been suggested heretofore to print by means of flat printing members Without usin a sponging liquid, but as far as my knowledge goes, this problem has not been solved in a satisfactory manner. All attempts that have been made heretofore to substitute for the sponging or wiping water a means, such as the addition of acids or metallic salts to the preparing liquid, have proved a failure since, as soon as moistening is dispensed with, the printing member will at once take up and hold the printing ink outside of the'figures to be typed so that accurate printing is impossible.

It has also been proposed heretofore, to mix so-called tone-protecting metallic salts or acids with the printing ink instead of the preparing liquid. All these prior suggestions, however, failed to be reliable substitutes for the old moistening operation the more so since they involve the disadvantage of injuriously affecting the prints and dama ing the metal, so that the efficiency and life 0 the printing member will be considerably reduced thereby.

I have found, after much study and research, that absolutely tone-free prints or copies can be obtained by means of flat ing members if, in the case of employing alu minium as a printing metal, both the preparing liquid and the printing ink are mixed with the metallic nitrates or sulfates such as aluminum nitrate or sulphate. The nitrates of nickel, iron and copper can also be used. These salts do not injuriously affect the print nor the aluminium, and I have found that the said salts 'havea tone-protecting effect and at the same time act to improve the quality of the print, in contradistinction to the means hitherto employed or suggested, so that a great many more copies can be taken than hitherto possible in the wet-offset printing process.

Moreover, the use of metallic nitrates or sulfates, according to m invention, considerably simplifies the troub esome and precarious re rinting process as hitherto practised and a ords a more reliable base to the latter. When an aluminium plate is directl written upon or covered with drawingsor t e script- FRANKFORT-ON-THETMAIN, AMERICAN MULTIGRAPH COMPANY, or CLEVELAND,

DRY-OFFSET-PRINTING PROCESS iwith alithographic crayon,

litho raphy for locating 2.

GERMANY, ASSIGNOB TO THE OHIO, A COIBCPORATION OF and in Germany January 20, 192').

ural characters are copied thereon by means of a suitable reprinting ink, it will be sufiicient to moisten the plate inclusive of the scriptural characters with an aqueous solu tion of a metallic nitrate or sulfate and to apply thereto a printing ink which is likewise mixedwith a metallic nitrate or a sulfate. The printing characters will be improved or enriched thereby and absorb the ink readily, whereas all other parts of the printing plate repel the ink thoroughly and remain absolutely tone-free. Anyusual fatty ink or fatty pencil may be employed for writing the scriptural characters. In case of type-writing a black ink-ribbon of conventional'nature will do, but particularly a ribbon out from or consisting of ordinary carbon paper will give the best results. A carbon paper ribbon is inexpensive and has the furtheradvantage of roducing more precise, sharp and well-define copies.

The steps of the process are as follows:

1. Ink image is located on an ordinary planographic metal plate by any suitable process, such as drawing directly on the plate transferring a design-previously prepared on transfer paper, or by any other methods well known in photo an image on a plate.

he plate is treate by covering the surface with a solution prepared in accordance with the present ap lication. This solution is prepared by disso ving about 5% of metallic nitrates or sulphates or both in any kind of suitable liquid such as water.

3. The plate is now prepared for printin by rubbing the printin surface w1th sai solution in order to con ition it for the ink.

This conditioning results from the solution lll hand for applying on the plate. This ink is composed of any known common eff-set ink containg for instance linseed oiland lampblack or other coloring matter together with 3 to 8% of metallic nitrate or sulphate, or both, intimately mixed with the other ingredients In the case of an aluminum plate, aluminum nitrate or aluminum sulphate would be used. i

'4. The plate needs no dampening and the special ink is now appiied directly on the dried printing surface which does not retain ink on non-image areaswhich have adry protective coating due to the treatment described.

5." The plate is new ready for printing and any number of copies can be made" from the plate on which the ink is renewed by repeated applications. The supply of crystals or particles in the non-image areas is re- "plenished from the metallic nitrate or sulphate salts contained in the ink.-

"i Apparently the metallic nitrate or sulphate solution applied to the plate leaves a deposit of fine particles or crystals of the metallic nitrate or sulphate on the plate, which particles adhere to the plate (assuming the latter is a fat-free substance) due to the natural adhesive quality of these particles or crystals when applied to non-greasy substances. So far as I know, there is no actual chemical action on the plate. Since the printing ink contains a percentage of the metallic nitrates or sulphates, and since these ingredients have no aflinity for the ink, and are not chemically combined therein but mechanically mixed with the ink, the particles of metallic nitrates or sulphates in the ink able under replenish the supply of particles on the plate, each time the roller bearing the ink is applied to the plate. Naturally, where the image appears on the plate (formed by fatty ink or pencil or by generally known photographic steps, or any known equivalent of the above), the image bearing parts of the plate will not readily take up any of the particles of the metallic nitrates or sulphates from the ink, because such fatty ink image or equivalent naturally repels these particles.

It will be understood that I have mentioned an aluminum plate in the above disclosure by way of example only, and that the invention is applicable to substancesother than aluminum which are suitable for use as printing plates. I believe these materials include only those which are fat-free.

It will e evident that my invention, while still being adhered to in its main essentials,

may be varied and adapted in many ways, ac-v I cording to requirements desired or most suitdifi'erent circumstances.

I claim:

1. A printing process, eomprising the following steps, first,bprepar1n a print? g plate with an image to e printe and with a substance carrying a material selected from the group containing metallic nitrates and metallic sulphates, and then printing from such plate with an ink carrying a material selected from said group.

2. A printing process consisting in providiug a text directly on a plate by means of a fatty ink and then treating said plate with a solution of a material selected from the group consisting of metallic nitrates and metallic sulphates and finally applying a fatty ink containing material selected from said group.

3. A printing process in which a printing plate is first provided with a text by means of a fatty ink, second, treatin a plate with a solution of a material selectef from a group containing metallic nitrates and metallic sulphates and printing from said plate with an ink which contains material from said group.

4;. A. printing process consisting in providing a text directly on a plate by means of a fatty ink and then treating said late with a solution of metallic nitrate an printing from said plate with an ink containing a metallic nitrate.

In testimony whereof I atfix my signature. 

